The past several years have been witness to a renewed interest in the environment. The special attention afforded so-called "green" products and methods of production attest to the fact that commercial viability is not always contrary to resource conservation. Often, environmental regulations and/or restrictions provide the impetus for innovative methods and apparatus.
A case in point is the recent legislative trend toward banning landfill disposal of various waste materials. Of course, many hazardous chemical and biological wastes have long been restricted, but with available landfill space becoming increasingly scarce, common yard and various related forms of vegetative organic wastes will soon require alternate means of disposal. Municipalities and other levels of government are faced with an urgent and growing problem.
The advantages of composting or decomposing organic material to provide various fertilizers and/or soil amendments are well-known. The challenge has always been one of adapting backyard garden techniques to processes capable of handling large volumes, such as those typically generated by municipalities, in a safe, environmentally-conscious manner. The problem has been compounded in recent years by the budgetary constraints under which most governmental units operate. Economy and fiscal responsibility are, thus, additional on-going concerns in the art.
The prior art includes a variety of attempts to produce an apparatus or derive a method to decompose or compost waste organic material through the metabolic activity of aerobic bacteria. Most provide only limited success. U.S. Pat. No. 3,934,999 describes use of an aqueous bacterial inoculant and depends on absorption of solar heat to decompose a small amount of dry organic material placed in a common home garbage bag. A number of evenly spaced apertures in the bag allow passive movement of air and facilitate composting. Periodic, manual agitation of material is required and possible only because the method is restricted to exceedingly small volumes.
U.S. Pat. No. 3,756,784 is directed to a complex apparatus for the sequential composting of domestic refuse and includes a plurality of essentially immovable vertically-disposed chambers, each with its own agitator, water supply, and air supply. The rates of addition of air and water are a function of temperature and carbon dioxide levels in each chamber. A varying combination of air, water, and agitation must be accurately administered to maintain aerobic conditions in each chamber.
U.S. Pat. No. 4,302,546 discloses a constantly rotating tank-like apparatus to recycle animal wastes. Carbonaceous filler materials must be added to control moisture content. Continual, low flow-rate aeration facilitates decomposition. Exhaust air is past through a scrubber to eliminate foul-smelling components which would otherwise pollute the surrounding atmosphere.
U.S. Pat. Nos. 3,138,447 and 3,930,799 are directed to a process and apparatus, respectively, for producing fertilizer from organic and inorganic municipal garbage. Low flow-rate aeration is aided by constant "tumbling" to prevent air channel formation. Moisture is first introduced to enhance decomposition via the addition of sewerage sludge then removed during a later drying phase. Temperature and carbon dioxide levels are monitored throughout decomposition.
U.S. Pat. No. 4,230,676 describes an apparatus and method for decomposition using exposed windrows of organic material. Integral to both the apparatus and method is a microprocessor which monitors temperature, air/moisture content, and pH of the windrowed material. A complex, adjustable injector configuration makes any additions/corrections necessary in response thereto.
Various prior art sources teach the use of a Beltsville or modified Beltsville system, which is necessarily limited to composting small volumes of material under tropic or warm weather conditions through use of a solar forced-air collector. Low-rate aeration and initial addition of water to loosely-arranged material characterize methods of this type. The apparatus used therewith typically includes overlapping sheets of plastic to catch rain water.
These are but a few examples of the prior art. Other methods and/or apparatus may be characterized as involving extensive waste analysis and monitoring, supplemental heat supplies, and agitation, among other steps or components. As is evident, a considerable number of drawbacks and problems exist in the prior art relating to the beneficial decomposition of organic waste materials.
There is a need for an improved aerobic decomposition method to more fully utilize the advantages associated with re-using waste materials of the sort and, at the same time, provide for a feasible, environmentally-safe alternative to landfill disposal.